Method of and furnace for burning fine granular substances in moist condition



March 19, 1968 R. JUNG 3,373,704

METHOD OF AND FURNACE FOR BURNING FINE GRANULAR SUBSTANCES IN MOISTCONDITION Filed May 9, 1966 4 Sheets-Sheet 1 rior art IA/VZA/ 7'08 March19, 1968 R JUNG 3,373,

METHOD OF AND FURNACE FOR BURNING FINE GRANULAR SUBSTANCES IN MOISTCONDITION Filed May 9, 1966 4 Sheets-Sheet 2 prior art! l/WE/l/TUB March19, 1968 R JUNG 3,373,704

METHOD OF AND FURNACE FOR BURNING FINE GRANULAR SUBSTANCES IN MOISTCONDITION Filed May 9, 1966 4 Sheets-Sheet 3 WI fA TOH March 19, 1968 R.JUNG 3,373,704 METHOD OF AND FURNACE FOR BURNING FINE GRANULARSUBSTANCES IN MOIST CONDITION Filed May 9, 1966 4 Sheets-Sheet 4 WWW m25% a? 73 United States Patent Ofi ice 3,373,704 METHOD OF AND FURNACEFOR BURNING FINE GRANULAR SUBSTANCES IN MOIST CONDITION Richard Jung,Gurnmersbach, Germany, assignor to L. & C. Steinmuller G.m.b.H.,Gummersbach, Germany Filed May 9, 1966, Ser. No. 548,487 Claimspriority, application Germany, May 15, 1965, St 23,827 6 Claims. (Cl.110-7) ABSTRACT OF THE DISCLOSURE A method of and furnace for burningfine granular substances in moist condition characterized primarily inthat combustion air is at an acute angle directed toward at least one ofthe respective adjacent front or rear walls in downward direction alongsaid wall or walls, while a locally defined back and upward flow area ofthe combustion flow is created, and at least the by far major portion ofthe wet fine granular substance to be injected is, in the form of jets,in upward direction injected into the lower end of the back and upwardflow area of the combustion air flow.

The present invention relates to a method of and furnace for burningfine granular substances in moist condition.

It is known to convey through nozzle means into a combustion chamber thewaste liquor obtained during the production of cellulose together withwater steam as atomizing substance, and subsequently to burn the thusobtained mixture in a hot air c-ountercurrent. The course and the resultof the combustion are due to the reaction inertia of the liquordependent to a great extent on the course of the flow of the combustionair and on the flue gases being'formed. This tendency has not been sufiiciently taken into consideration with heretofore known structures of thetype involved so that such combustion chambers are not satisfactory froma combustion standpoint.

The combustion air is blown into the preferably prismatic combustionchamber from which the flue gas flows downwardly into the next fluethrough the ceiling of from two to four rows of nozzles parallel to thefront wall while flowing from the top in jets parallel to each other.The liquor is passed into the combustion chamber through a plurality ofatomizing nozzles extending through the front wall and the side wall.These last mentioned nozzles are so arranged that when the individualjets can spread in a cone-shaped manner without being interfered with,the atomized liquor would approximately be uniformly distributed overthe chamber cross section in the neighborhood of the chamber ceiling.Since, however, the originally parallel air jets combine in the chamberto one or more air strands non-uniformly distributed over the crosssection of the chamber, and since between the said strands the hot fluegas flows back from an area of advanced combustion, the length of thepaths over which the individual droplets of the atomized liquor flow inthe combustion chamber vary considerably. Thus, for a liquor componentinjected into an air str-and, a retarded combustion is to be expectedwhich may be delayed up to the next following flue, whereas the liquorcomponent carried along in a hot return flow will completely burn outwithin the chamber.

It is, therefore, an object of the present invention to provide a methodof burning fine granular substances in 3,373,704 Patented Mar. 19, 1968liquid condition in a combustion chamber, which will overcome thehereabove mentioned drawbacks.

It is another object of this invention to provide a method as set forthin the preceding paragraph, in which the individual jets will combine toa flow which will be uniformly distributed over the width of the wall ofthe combustion chamber.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawings, in which:

FIGS. 1 and 2 illustrate a method of burnin fine granular moist materialin the manner heretofore known.

FIGS. 3 and 4 illustrate in corresponding views the method according tothe present invention, FIG. 4 differing from FIG. 3 in that one nozzlerow only is provided.

The above outlined different lengths of the combustion paths and theuncertainty inherent thereto in connection with the design and operationof such combustion chambers can be overcome according to the presentinvention by producing in the combustion chamber a flow form with apronounced locally fixed return flow area. To this end, in conformitywith the present invention, the air nozzles are suitably arranged andthe entire liquor is injected into this area. Such a flow form isobtained for instance when introducing air through two rows of nozzlesarranged in the chamber ceiling symmetrically with regard to the centrallongitudinal plane while the air jets leaving the nozzles are inclinedrelative to the adjacent front and rear walls at an angle of from 5 to10. As a result thereof, a downward flow is obtained which is uniformlydistributed over the width of the chamber and between the said flowalong the walls there is obtained an extended double turbulence with acentral return flow of hot combustion gases directed toward the ceiling.In conformity with the present invention, the liquor is bloWn into thisreturn flow through a plurality of upwardly directed atomizing nozzles.

The'method according to the invention may also be realized by guidingthe combustion air downwardly only along the rear wall and by guidingthe hot return flow with the injected liquor upwardly along the frontwall. In both instances, the fuel will pass into the combustion air flowonly after it has reached the vicinity of the combustion chamberceiling. In the preceding section, the aqueous component of the liquorevaporates, and the remainingdry substance is ignited. After thisrefining operation of the fuel which in its initial condition is ratherreaction .inert, only a relatively short path is necessary for acomplete combustion in the hot air flow.

In order more clearly to bring out the difference between the heretoforeknown method and the method according to the present invention, FIGS. 1to 4 show the characteristic nozzle arrangements and the flow formsobtained thereby.

More specifically referring to the drawings, FIG. 1 shows a longitudinalsection through a combustion chamber 1 with nozzle rows 3 and 4 in theceiling 5 of the chamber for supplying combustion air, the longitudinalsection being substantially perpendicular to the front wall 2. FIG. 1also shows atomizing nozzles 7 extending through opening 6 in front Wall2. The arrangement of the nozzles is evident from FIG. 2 in thelongitudinal plane perpendicular to the front wall.

The air jets which flow into the combustion chamber along paths parallelto the longitudinal walls combine in conformity with the drawn flowlines to a single strand which engages the front wall and one of the twoside walls 8 or 9. In that area which is not covered by this strand, anextensive return circulatory turbulence with a return flow preferablydirected along the return wall 10 will occur. In this unsymmetric flowthe starting conditions for the course of the reaction of the liquor injected into the return flow or the air strand vary consid erably withregard to each other. The liquor component passing directly into the airstrand will in view of the retarded ignition even at an increased excessin air not burn out completely or only in an inadmissible great distancein a downfiow direction of the combustion chamber.

In contrast to this heretofore known method illustrated in connectionwith FIGS. 1 and '2, with the method according to the present invention,as illustrated in FIGS. 3 and 4, the air jets leaving the nozzle rows 3and 4 are directed against the rear wall 8 and the front wall 2. In thisconnection, the illustrated symmetric flow form with the central returnflow will be obtained which carries the injected liquor. This returnflow is combined with the partial fiows of the combustion chamber whichflow downwardly along the walls. Moreover, the inclined position of theair nozzles brings about that the individual jets expand along the wallsin a direction perpendicular to the intermediate plane and thus flowtogether to a flow which is uniformly distributed over the width of thewall. The constriction of the downward flow detached from a side wall asit occurs with wall parallel feed according to FIG. 2, will not occur.

FIG. 4 shows an arrangement with only one nozzle row 3 directed towardthe rear wall 8. In this instance, the liquor is injected into thereturn flow area adjacent to the front wall. The inclined position ofthe ceiling favors the return flow into the outer zone leading to themouth area of the air nozzles.

The method according to FIG. 3 or 4 is also suitable for burning moistfine granular substances, as for instance coal sludge or slurry, whichis dried within the hot return flow and ignited and can be burned whenmixed with the preheated air.

It is, of course, to be understood that the present invention is, by nomeans, limited to the particular method set forth above but alsocomprises any modifications within the scope of the appended claims.

What I claim is:

1. A method of burning moist and wet fine granular substance in acombustion chamber having at least approximately parallel front and rearwalls, which includes the steps of: passing combustion air at an acuteangle toward at least one of the respective adjacent one of said wallsin downward direction along the same while creating a locally definedback and upward flow area of the combustion air flow, and directing atleast the by far major portion of the said wet fine granular substancein the form of jets in upward direction into the lower end of the saidback and upward fiow area of said combustion air flow.

2. A method according to claim 1, which includes the step of: passingthe combustion air in downward direc tion in the form of two spacedrelatively fiat flows along said front and rear walls respectively whilesaid flows extend on opposite sides of the longitudinal central plane ofsaid combustion chamber and while creating the locally defined back andupward fiow area of the combustion air flow along the said longitudinalcentral plane.

3. A method according to claim 1, which includes the steps of: passingthe combustion air in downward direction in the form of a relativelyfiat flow along said rear wall only while creating the locally definedback and upward flow area of the combustion air flow along said frontwall.

4. A furnace comprising a combustion chamber having a front and a rearwall and a ceiling, first nozzle means arranged in said ceiling andhaving the mouths thereof directed at an acute angle toward at least oneof the respective adjacent walls for passing combustion air downwardlyin the form of a relatively flat flow along at least one of said walls,and second nozzle means having the mouths thereof directed substantiallyvertically upwardly and spaced from at least one of said walls by atleast approximately half of the distance between said front and rearwalls for injecting waste liquor into the lower end of the back andupward flow area of the combustion air flow halfway between said frontand rear walls.

5. A furnace according to claim 4, in which said first nozzle meanscomprises a first row of nozzles with the mouths thereof directed at anacute angle to said rear wall and also includes a second row of nozzleswith the mouths thereof directed at an acute angle toward said frontwall, said acute angles substantially equalling each other, the mouthsof said second nozzle means being located at least approximately alongthe central plane between said front and rear walls.

6. A furnace according to claim 4, in which said first nozzle means haveall of their mouths directed toward said rear wall, whereas the mouthsof said second nozzle means are adjacent said front walls for directingsaid substance along said front wall in the form of a relatively flatflow, said ceiling being inclined in upward direction so as to ascendfrom said front wall towardsaid rear Wall.

References Cited UNITED STATES PATENTS 1,770,987 7/1930 Lundgren -282,531,810 11/1950 Fyffe. 2,582,792 1/1952 Paren. 3,306,?) 34 2/1967Goubsky 1584 JAMES W. WESTHAVER, Primary Examiner.

